JP2020506630A - Method and apparatus for performing side link communication in a wireless communication system - Google Patents

Abstract

The present invention discloses a method for performing site link communication in a wireless communication system, and an apparatus therefor. More specifically, the method performed by the first terminal may include a resource pool allocation information indicating at least one resource pool among a plurality of preset resource pools from the base station. And identifying a specific sidelink resource for a second terminal in the at least one resource pool; and transmitting the identified specific sidelink resource to the second terminal. Transmitting the allocated signal, the specific side link resource may be allocated for a signal for performing a side link measurement between the first terminal and the second terminal.

Description

  The present invention relates to a wireless communication system, and more particularly, to a method for performing side link communication in a group unit and an apparatus supporting the method.

  Mobile communication systems have been developed to provide voice services while ensuring user activity. However, mobile communication systems have expanded beyond voice as well as data services, and are now expanding as explosive increases in traffic cause resource shortages and users demand faster services. There is a demand for an improved mobile communication system.

  The requirements of the next generation mobile communication system are to accommodate large and explosive data traffic, breakthrough increase in transmission rate per user, accommodate greatly increased number of connected devices, and very low end-to-end delay (End- It must be able to support to-end latency and high energy efficiency. To this end, multiple connectivity (Dual Connectivity), massively multiple input / output (Massive Multiple Input Multiple Output), full-duplex (In-band Full Duplex), non-orthogonal multiple access (NOMon-on-on-multiple-on multiple access) are available. Various technologies, such as Access, Super Wideband support, and Device Networking, are being studied.

  The present specification proposes a method for performing side link communication in a wireless communication system, and an apparatus therefor.

  More specifically, the present specification proposes a measurement procedure and a synchronization method for performing side link communication on a group basis.

  For this reason, this specification proposes a method of setting a resource region (resource pool) for group measurement.

  In addition, this specification proposes a method of transmitting and relaying signals for group measurement.

  In addition, this specification proposes a method of setting a priority of a synchronization reference in group communication.

  In addition, the present specification proposes a method of setting a time point of a synchronization reference and a communication execution method.

  In addition, this specification proposes a method of relaying a synchronization signal related to group communication.

  The technical problem to be solved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned above have ordinary knowledge in the technical field to which the present invention belongs from the following description. Should be clearly understood by the person.

  In the method for performing the side link communication in the wireless communication system according to the embodiment of the present invention, the method performed by the first terminal may include a method of transmitting at least one resource from a plurality of preset resource pools from a base station. Receiving resource pool allocation information indicating a pool; identifying a specific sidelink resource for a second terminal in the at least one resource pool; Transmitting a signal for allocating the identified specific side link resource to the two terminals, wherein the specific side link resource is determined by a side link measure between the first terminal and the second terminal. Allocated for signals for ment).

  Also, in the method according to the embodiment of the present invention, the at least one resource pool may be allocated for a specific terminal group to which the first terminal and the second terminal belong.

  Further, in the method according to the embodiment of the present invention, the signal for performing the side link measurement is at least one of identification information of the specific terminal group or information of a terminal order within the specific terminal group. One.

  In addition, in the method according to the embodiment of the present invention, the specific side link resource is identified according to a resource order set for the second terminal, and the resource order is set in advance. It can be set based on a resource pattern that has been assigned.

  In the method according to the embodiment of the present invention, the preset plurality of resource pools includes one or more sub-resource pools set for each terminal group, and the resource pool assignment information includes an upper layer. May be received via higher layer signaling.

  In the method according to the embodiment of the present invention, the signal for performing the side link measurement may include a counter indicating the validity of the signal.

  In addition, the method according to an embodiment of the present invention may include transmitting information indicating a new resource pool for transmitting a signal for performing the side link measurement to the second terminal before the counter expires. The method may further include a step, wherein the new resource pool belongs to the preset plurality of resource pools.

  In the method according to the embodiment of the present invention, the specific side link resource is a received signal energy value (received signal) measured for one or more side link resources constituting the at least one resource pool. It can be determined using at least one of an energy value or a CBR (Channel Busy Ratio) value.

  In the method according to the embodiment of the present invention, the preset plurality of resource pools include a specific resource pool for a fall-back operation associated with the side link measurement procedure. The method may further include transmitting a signal for performing the side link measurement on the specific resource pool.

  A first terminal for performing side link communication in a wireless communication system according to an embodiment of the present invention, comprising: a transmitting / receiving unit for transmitting / receiving a wireless signal; and a processor operatively connected to the transmitting / receiving unit, the processor comprising: Receives, from a base station, resource pool allocation information indicating at least one resource pool among a plurality of preset resource pools, and performs resource pool allocation information on the at least one resource pool in the at least one resource pool. Identifying a specific sidelink resource for the two terminals and controlling to transmit a signal to allocate the identified specific sidelink resource to the second terminal; Is the first terminal And a signal for performing a side link measurement between the UE and the second terminal.

  According to the embodiment of the present invention, when performing side link communication in group units, there is an effect that efficient group management is possible by measuring using signals transmitted and received between terminals.

  Further, according to the embodiment of the present invention, by allocating resources of another terminal to a specific terminal, a terminal existing outside the coverage of the base station can also perform signal transmission between terminals, which is efficient. There is an effect that measurement of a group can be performed.

  In addition, according to the embodiment of the present invention, there is an effect that an adaptive synchronization procedure can be performed according to the status of terminals belonging to a group.

  The effects that can be obtained by the present invention are not limited to the effects mentioned above, and other effects that are not mentioned are clearly understood by those having ordinary knowledge in the technical field to which the present invention belongs from the following description. Should be.

The accompanying drawings, which are included as part of the detailed description to aid in understanding the invention, provide embodiments for the present invention and, together with the detailed description, explain the technical features of the present invention.
FIG. 2 is a diagram illustrating an example of an overall NR system structure to which the method proposed in this specification can be applied. FIG. 3 is a diagram illustrating a resource grid for one downlink slot in a wireless communication system to which the present invention can be applied. 1 shows a structure of a downlink subframe in a wireless communication system to which the present invention can be applied. 4 illustrates a structure of an uplink subframe in a wireless communication system to which the present invention can be applied. FIG. 3 is a diagram illustrating elements for a direct terminal-to-terminal (D2D) technique. It is a figure showing an example of composition of a resource unit. An example of a configuration of a resource area for group management to which the method proposed in this specification can be applied is shown. 10 shows another example of the configuration of a resource area for group management to which the method proposed in this specification can be applied. 4 shows an example of a resource allocation method for signals for group measurement to which the method proposed in this specification can be applied. 5 shows an example of a signal relay operation for measuring a group to which the method proposed herein can be applied. 4 shows an example of signaling between a base station and a terminal performing side link communication to which the method proposed in this specification can be applied. 1 illustrates a block diagram of a wireless communication device to which a method proposed in this specification can be applied. 1 illustrates a block diagram of a communication device according to an embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the invention, and not to illustrate the only embodiments in which the invention may be practiced. . The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it should be understood by those skilled in the art that the present invention may be practiced without such specific details.

  In some instances, well-known structures and devices are omitted or shown in block diagram form with a focus on the core function of each structure and device to avoid obscuring the concepts of the present invention. it can.

  In this specification, a base station has a meaning as a terminal node of a network that directly communicates with a terminal. In this document, a specific operation described as being performed by a base station may be performed by an upper node of the base station in some cases. That is, in a network including a plurality of network nodes including a base station, various operations performed for communication with a terminal can be performed by the base station or another network node other than the base station. It is. The “base station (BS: Base Station)” includes a fixed station (Node), a Node B, an eNB (evolved-Node B), a BTS (base transceiver system), an access point (AP: Access Point), and a Gnb (next generation). , General NB, gNodeB). In addition, the 'Terminal' may be fixed or mobile, and may include UE (User Equipment), MS (Mobile Station), UT (User Terminal), MSS (Mobile Subscriber Station), and SS (Mobile Subscriber Station). Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless Terminal), MTC (Machine-Type Communication) device, M2M (Machine-to-Machine) device, D2D-Dev-Dev (Dev-Dev-Dev) device Can be replaced.

  Hereinafter, downlink (DL) means communication from a base station to a terminal, and uplink (UL: uplink) means communication from a terminal to a base station. On the downlink, the transmitter may be part of a base station and the receiver may be part of a terminal. On the uplink, the transmitter may be part of a terminal and the receiver may be part of a base station.

  Certain terms used in the following description are provided to facilitate understanding of the present invention, and the use of such specific terms may be changed to different forms without departing from the spirit of the present invention.

The following technologies, CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), It can be used for various wireless connection systems such as NOMA (non-orthogonal multiple access). CDMA can be realized by a radio technology (radio technology) such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA is a global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM (enhanced data rates for GSM (registered trademark) evolving technology such as GSM (registered trademark) evol. OFDMA can be implemented by wireless technologies such as IEEE 802.11 (WiFi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). UTRA is part of UMTS (universal mobile telecommunications system). ^{3GPP (3 rd generation partnership project)} LTE (longterm evolution) is a part of E-UMTS that uses E-UTRA (evolved UMTS), employs OFDMA on the downlink and SC-FDMA on the uplink adopt. LTE-A (advanced) is an evolution of 3GPP LTE.

  Embodiments of the present invention are supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP, and 3GPP2. That is, steps or portions of the embodiments of the present invention that are not described in order to clearly show the technical idea of the present invention are supported by the document. Also, all terms disclosed in this document can be explained by the standard document.

  In order to clarify the description, the technology will be focused on 3GPP LTE / LTE, NR (New RAT), but the technical features of the present invention are not limited to this.

General system

  FIG. 1 shows a structure of a radio frame in a radio communication system to which the present invention can be applied.

  The 3GPP LTE / LTE-A supports a type 1 radio frame (radio frame) structure applicable to FDD (Frequency Division Duplex) and a type 2 radio frame structure applicable to TDD (Time Division Duplex).

  In FIG. 1, the size of the radio frame in the time domain is represented by a multiple of a time unit of T_s = 1 / (15000 * 2048). Downlink and uplink transmissions consist of radio frames having a section of T_f = 307200 * T_s = 10 ms.

  FIG. 1A illustrates the structure of a type 1 radio frame. The type 1 radio frame may be applied to a full duplex and a half duplex FDD.

  A radio frame is composed of ten subframes. One radio frame is composed of 20 slots having a length of T_slot = 15360 * T_s = 0.5 ms, and each slot is assigned an index from 0 to 19. One subframe is composed of two consecutive slots in a time domain, and subframe i is composed of a slot 2i and a slot 2i + 1. The time required to transmit one subframe is called TTI (transmission time interval). For example, the length of one subframe may be 1 ms, and the length of one slot may be 0.5 ms.

  In FDD, uplink transmission and downlink transmission are partitioned in the frequency domain. While there is no limit on full-duplex FDD, in half-duplex FDD operation the terminal cannot transmit and receive at the same time.

  One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in a time domain, and includes a number of resource blocks (RBs) in a frequency domain. Since 3GPP LTE uses OFDMA in the downlink, an OFDM symbol is for representing one symbol period. An OFDM symbol can be referred to as one SC-FDMA symbol or symbol section. A resource block is a resource allocation unit and includes a plurality of continuous subcarriers in one slot.

  (B) of FIG. 1 shows a type 2 frame structure (frame structure type 2). The type 2 radio frame is composed of two half frames each having a length of 153600 * T_s = 5 ms. Each half frame is composed of five subframes having a length of 30720 * T_s = 1 ms.

  In a type 2 frame structure of the TDD system, an uplink-downlink configuration is a rule indicating whether an uplink and a downlink are allocated (or reserved) for all subframes. It is. Table 1 shows an uplink-downlink configuration.

  Referring to Table 1, for each subframe of a radio frame, "D" represents a subframe for downlink transmission, "U" represents a subframe for uplink transmission, and "S" is , DwPTS (Downlink Pilot Time Slot), a protection section (GP: Guard Period), and UpPTS (Uplink Pilot Time Slot), which represent a special subframe (special subframe).

  DwPTS is used for initial cell search, synchronization or channel estimation in a terminal. UpPTS is used to synchronize channel estimation at the base station with uplink transmission synchronization of the terminal. GP is a section for removing interference generated on the uplink due to a multipath delay of a downlink signal between the uplink and the downlink.

  Each subframe i is composed of a slot 2i and a slot 2i + 1 each having a length of T_slot = 15360 * T_s = 0.5 ms.

  The uplink-downlink configuration can be classified into seven types, and the position and / or the number of downlink subframes, special subframes, and uplink subframes differ for each configuration.

  The point in time when the downlink is changed to the uplink or the point in time when the uplink is switched to the downlink is referred to as a switching point. The switching point periodicity refers to a cycle in which an uplink subframe and a downlink subframe are repeatedly switched in the same manner, and 5 ms or 10 ms is supported. When the period of the downlink-uplink switching point is 5 ms, the special subframe S exists every half frame, and when the period of the downlink-uplink switching point is 5 ms, the special subframe S is first. Exists only in the half-frame of.

  In all configurations, the 0th and 5th subframes and DwPTS are sections for only downlink transmission. UpPTS and subframes A subframe immediately connected to a subframe is always a section for uplink transmission.

  Such an uplink-downlink configuration is system information, and the base station and the terminal may all know. The base station can notify the terminal of the change in the uplink-downlink allocation state of the radio frame by transmitting only the index of the configuration information every time the uplink-downlink configuration information changes. Also, the configuration information is a kind of downlink control information, and can be transmitted via a PDCCH (Physical Downlink Control Channel) like other scheduling information, and can be transmitted as broadcast information via a broadcast channel. It can be transmitted in common to all terminals in the cell.

  Table 2 shows the configuration of the special subframe (the length of DwPTS / GP / UpPTS).

  The structure of the radio frame according to the example of FIG. 1 is merely an example, and the number of subcarriers included in the radio frame, the number of slots included in the subframe, and the number of OFDM symbols included in the slot are variously changed. Can be done.

  FIG. 2 is a diagram illustrating a resource grid for one downlink slot in a wireless communication system to which the present invention can be applied.

  As shown in FIG. 2, one downlink slot includes a plurality of OFDM symbols in the time domain. Here, one downlink slot includes seven OFDM symbols, and one resource block includes twelve subcarriers in the frequency domain, but the present invention is not limited thereto. .

  Each element on the resource grid is a resource element, and one resource block (RB) includes 12 × 7 resource elements. The number N ＾ DL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth.

  The structure of the uplink slot may be the same as the structure of the downlink slot.

  FIG. 3 shows a structure of a downlink subframe in a wireless communication system to which the present invention can be applied.

  As shown in FIG. 3, in the first slot in the subframe, up to three previous OFDM symbols are control regions to which control channels are allocated, and the remaining OFDM symbols are PDSCH (Physical Downlink). This is a data region (data region) to which a shared channel is assigned. Examples of downlink control channels used in the 3GPP LTE include Physical Control Format Indicator Channel (PCFICH), Physical Downlink Control Channel (PDCCH), and PHICH (Physical Hybrid Q-Ray Hybrid-AR).

  The PCFICH is transmitted in the first OFDM symbol of the subframe and carries information about the number of OFDM symbols used for transmission of the control channel in the subframe (ie, the size of the control region). The PHICH is a response channel for the uplink, and carries an ACK (Acknowledgment) / NACK (Not-Acknowledgment) signal for HARQ (Hybrid Automatic Repeat Request). Control information transmitted via the PDCCH is referred to as downlink control information (DCI). The downlink control information includes uplink resource allocation information, downlink resource allocation information, or an uplink transmission (Tx) power control command for any terminal group.

  The PDCCH includes DL-SCH (Downlink Shared Channel) resource allocation and transmission format (also referred to as downlink grant), UL-SCH (Uplink Shared Channel) resource allocation information (also referred to as uplink grant), PCH Paging information in a paging channel, system information in a DL-SCH, resource allocation for an upper-layer control message such as a random access response transmitted from a PDSCH, arbitrary , A set of transmission power control commands for individual terminals in the terminal group, activation of VoIP (Voice over IP), and the like.A plurality of PDCCHs can be transmitted in a control region, and a terminal can monitor the plurality of PDCCHs. The PDCCH is composed of a set of one or a plurality of continuous control channel elements (CCEs). The CCE is a logical allocation unit used to provide a coding rate according to a state of a radio channel to a PDCCH. The CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of available bits of the PDCCH are determined by the relationship between the number of CCEs and the coding rate provided by the CCEs.

  The base station determines a PDCCH format according to the DCI to be transmitted to the terminal, and attaches a CRC (Cyclic Redundancy Check) to the control information. In the CRC, a unique identifier (referred to as RNTI (Radio Network Temporary Identifier)) is masked according to the owner or use of the PDCCH. In case of a PDCCH for a specific terminal, a unique identifier of the terminal, for example, C-RNTI (Cell-RNTI) can be masked in the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier, for example, a P-RNTI (Paging-RNTI) may be masked in the CRC. If the PDCCH is for system information, more specifically, a system information block (SIB), a system information identifier and an SI-RNTI (system information RNTI) can be masked in the CRC. RA-RNTI (random access-RNTI) can be masked in the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the terminal.

  EPDCCH (enhanced PDCCH) carries terminal-specific (UE-specific) signaling. The EPDCCH is located in a physical resource block (PRB) set unique to a terminal. In other words, as described above, the PDCCH may be transmitted in up to three previous OFDM symbols in the first slot in the subframe, while the EPDCCH may be transmitted in a resource region other than the PDCCH. The time point (ie, symbol) at which the EPDCCH starts in the subframe may be set to the terminal via higher layer signaling (eg, RRC signaling or the like).

  The EPDCCH includes a transmission format related to the DL-SCH, resource allocation and HARQ information, a transmission format related to the UL-SCH, resource allocation and HARQ information, an SL-SCH (Sidelink Shared Channel), and a PSCCH (Physical Sidelink Control Channel). It may carry relevant resource allocation information and the like. Multiple EPDCCHs may be supported and the terminal may monitor a set of EPCCHs.

  The EPDCCH may be transmitted using one or more continuous advanced CCEs (ECCEs), and the number of ECCEs per single EPDCCH may be determined for each EPDCCH format.

  Each ECCE can be composed of a plurality of enhanced resource element groups (EREGs). EREG is used to define the mapping of ECCE to RE. There are 16 EREGs for each PRB pair. Except for REs that carry DMRS in each PRB pair, all REs are numbered from 0 to 15 in order of increasing frequency and subsequent time.

  A terminal may monitor multiple EPDCCHs. For example, one or two EPDCCH sets may be set in one PRB pair in which a terminal monitors EPDCCH transmission.

  By combining different numbers of ECCEs, different coding rates for the EPCCH can be realized. The EPCCH may use localized transmission or distributed transmission, and the mapping of the ECCE to the RE in the PRB may change according to the localized transmission or the distributed transmission.

  FIG. 4 shows a structure of an uplink subframe in a wireless communication system to which the present invention can be applied.

  As shown in FIG. 4, the uplink subframe is divided into a control domain and a data domain in the frequency domain. A PUCCH (Physical Uplink Control Channel) that carries uplink control information is assigned to the control region. The data area is assigned a PUSCH (Physical Uplink Shared Channel) that carries user data. In order to maintain the single carrier characteristic, one terminal does not transmit PUCCH and PUSCH simultaneously.

  A resource block (RB) pair is allocated to a PUCCH for one terminal in a subframe. The RBs belonging to the RB pair occupy different subcarriers in each of the two slots. This is referred to as frequency hopping of the RB pair allocated to the PUCCH at a slot boundary.

D2D (Device-to-Device) communication

  FIG. 5 is a diagram for explaining elements for a direct terminal-to-terminal (D2D) technique.

  In FIG. 5, UE refers to a user terminal. However, when a network device such as an eNB transmits and receives signals according to a communication method with the UE, the corresponding network device can also be regarded as a type of UE. Hereinafter, the UE 1 selects a resource unit corresponding to a specific resource from a resource pool indicating a set of a series of resources, and transmits a D2D signal using the corresponding resource unit. Can work. UE2, which is the receiving UE, is configured with a resource pool to which UE1 can transmit a signal, and detects the signal of UE1 in the corresponding pool. Here, the resource pool can be notified by the base station when UE1 is in the range of the base station, and when the UE1 is out of the range of the base station, another UE notifies or is determined in advance. Resources can be determined. In general, a resource pool may include multiple resource units, and each UE may select one or more resource units to use for transmitting its own D2D signal.

  FIG. 6 is a diagram showing an embodiment of the configuration of the resource unit.

  Referring to FIG. 6, all frequency resources are divided into N_F resources, and all time resources are divided into N_T resources, so that a total of N_F * N_T resource units can be defined. Here, it can be described that the corresponding resource pool is repeated in a cycle of N_T subframes. Characteristically, one resource unit can be repeatedly displayed periodically as shown in FIG. Alternatively, in order to obtain a diversity effect in a time or frequency dimension, an index of a physical resource unit to which one logical resource unit is mapped may change to a predetermined pattern according to time. . The resource pool in such a resource unit structure may refer to a set of resource units that can be used by a UE transmitting a D2D signal.

  The resource pools described above can be subdivided into various types. First, the resource pools may be classified according to the content of the D2D signal transmitted in each resource pool. For example, the content of the D2D signal may be divided as follows, and a separate resource pool may be configured for each of the D2D signals.

  Scheduling assignment (SA): location of resources used for transmission of D2D data channel performed by each transmitting UE, MCS (modulation and coding scheme) required for demodulation of other data channels, MIMO transmission scheme and / or Or, a signal including information such as timing advance (timing advance). This signal can also be multiplexed and transmitted with D2D data on the same resource unit. In this specification, the SA resource pool may refer to a pool of resources in which the SA is multiplexed with the D2D data and transmitted, or may be referred to as a D2D control channel.

  D2D data channel: A resource pool used by a transmitting UE to transmit user data using resources specified via SA. If it is possible to multiplex and transmit with D2D data on the same resource unit, only the D2D data channel without the SA information may be transmitted in the resource pool for the D2D data channel. . In other words, on a separate resource unit in the SA resource pool, the resource elements used to transmit the SA information can still be used in the resource pool of the D2D data channel to transmit D2D data.

  Discovery channel: A resource pool for messages that allows a transmitting UE to transmit information such as its own ID and find itself for neighboring UEs.

  Contrary to the case described above, even when the contents of D2D signals are the same, different resource pools can be used according to the attributes of transmission and reception of D2D signals. As an example, even if the D2D data channel and the discovery message are the same, the transmission timing of the D2D signal is determined (for example, the transmission timing is determined when the synchronization reference signal is received, or the transmission is performed by applying a certain timing advance at the corresponding timing). Resource allocation scheme (eg, whether the eNB designates individual signaling transmission resources for individual transmitting UEs, or whether individual transmitting UEs select their own individual signaling resources in the pool) , Signal format (for example, the number of symbols occupied by one D2D signal in one subframe or the number of subframes used for transmitting one D2D signal), the signal strength from the eNB, the transmission power strength of the D2D UE, etc. May be again partitioned into different resource pools.

  In this specification, for convenience of explanation, the method in which the eNB directly instructs the transmission resource of the D2D transmitting UE in D2D or V2V communication is set to mode 1 or mode 3, the transmission resource area is set in advance, or the eNB is A method for designating a region and directly selecting a transmission resource by the UE is designated / defined as mode 2 or mode 4. In the case of D2D discovery, type 2 is used when the eNB indicates the resource directly, and type 1 is used when the UE selects the direct transmission resource in the preset resource area or the resource area specified by the eNB. Nominated / defined.

  The above-mentioned D2D may be referred to as a sidelink, and the SA is a physical sidelink control channel (PSCCH), a D2D synchronization signal (D2D synchronization signal) is a sidelink synchronization signal (sidelink synchronization signal). signal, SSS), a control channel for transmitting the most basic information before D2D communication transmitted together with the SSS, a physical sidelink broadcast channel (PSBCH), or a PD2DSCH (physical D2D synchronization channel) with another name. (Physical D2D synchronizatio channel)) and may be referred to. A signal for a specific terminal to notify that it is in the vicinity, where the signal may include the ID of the specific terminal, and such a channel may be referred to as a physical sidelink discovery channel (physical sidelink discovery channel). channel, PSDCH).

  Rel. In D2D of 12, only the UE of the D2D communication transmits the PSBCH together with the SSS, whereby the SSS is measured using the DMRS of the PSBCH. The out-coverage UE measures the DMRS of the PSBCH, measures the reference signal received power (RSRP) and the like of this signal, and determines whether or not the UE itself becomes a synchronization source (synchronization source). Will be.

  When the above-described direct communication is performed between the terminals, a specific terminal may perform group communication (eg, group transmission, group reception) as necessary. Here, the group communication may mean side link communication between terminals belonging to the group (that is, transmission and reception of control information and data via the side link). The group may be composed of one or more terminals, and may be set according to a service (service) supported by the terminal, a capability of the terminal, and the like.

  In the case of group communication, there may be a terminal that manages the group on behalf of the group, and may be referred to as a leading UE. In addition, the remaining terminals belonging to the corresponding group may be referred to as following terminals (following UEs). In addition, the leading terminal may be referred to as a relay terminal (relay UE), and the following terminal may be referred to as a remote terminal (remote UE).

  Specifically, in the group communication, a specific terminal in the group (eg, a head terminal, a terminal to which the corresponding authority and duty is assigned) is controlled by another terminal in the group (eg, a follow-up terminal) or other control (eg, : Broadcasting, Internet, multimedia, high-volume data traffic, etc.) applications.

  For example, a plateauning operation method / service in which vehicles are operated and / or communicated in groups with each other is an example of such a case. At this time, during the operation of the corresponding platen operation, basically, a specific terminal (eg, a head terminal) transmits a control signal, a message and / or other data to another terminal in order to guarantee a safe platenning service. Etc. may be sent. In addition, other UEs can also exchange signals with the specific terminal or another terminal.

  At this time, the content of signals and / or data exchanged between terminals may be determined by information generated by judging within the group, or may be determined outside the group (eg, other groups or networks, etc.). ) May be determined by the information generated in the above. That is, when the corresponding group exists within the range of a network such as a specific base station, a specific terminal (eg, a head terminal) receives a specific signal, message, and / or data from the base station, A method of transmitting to the terminal may also be considered. In other words, the method corresponds to a method in which a specific terminal in a group receives a signal, a message, and / or data of a base station in the form of a relay UE, and then receives the received signal, message, and / or data as a remote UE. To another terminal.

  As another example, in the case of the group communication, a representative terminal of a specific group may operate as a relay terminal in a mode of transmitting a signal, a message, and / or data to another remote terminal. Specifically, a representative terminal such as a smartphone, a smartphone, a tablet, or a wearable device exchanges signals, messages, and / or data with another smartphone, tablet, or wearable device. It can be in the form.

  The content of signals and / or data exchanged between such terminals may also be determined within the group and determined by the information generated, or generated outside the group (eg, other groups or networks, etc.). May be determined by the information to be performed. As an example, it is assumed that a specific smartphone exists as a representative terminal (or a relay terminal) within a network such as a specific base station. In this case, the specific smartphone may receive a specific signal, message, and / or data from the corresponding base station, and may transmit the specific signal, message, and / or data to another terminal (eg, another smartphone, tablet, wearable device, or the like).

  In the case of the group communication described above, the state of the terminals belonging to the corresponding group (eg, link quality between terminals, link state, etc.) may be continuously changed. Thereby, the configuration of the group, that is, the terminals configuring the group can be changed. As an example, a particular terminal may be removed from a particular group (eg, group leaving) or may belong to a new group (eg, group association). In particular, when terminal mobility is high, such as vehicle-to-vehicle (V2V) and / or vehicle-to-everything (V2X), the group configuration may be changed more frequently.

  When a terminal belongs to a base station (and / or a specific network), the base station (or a higher network entity (network entity) or the like) may receive the terminal through a signaling and / or a physical channel. Group (ie, terminal group (UE group)) can be managed. In this case, signaling and / or physical channels used for management in the group may exist or may be additionally defined as needed.

  However, when the mobility of the terminal is high, the base station connected to the terminal group may be frequently changed (eg, frequent handover), and it is not possible for the base station to manage the terminal group. Can be efficient. In this case, a procedure for directly managing such a terminal group between terminals may be required, and thus additional signaling and / or configuration may be required.

  Hereinafter, the present specification proposes a method of ascertaining a state of a terminal belonging to a terminal group (eg, a connection state) and performing a measurement procedure for performing a behavior suitable for a specific situation. The present specification also proposes a method of performing terminal synchronization that may be considered when the terminal performs the above-described group communication.

  Hereinafter, the embodiments described in the present specification are merely divided for convenience of description, and some configurations and features of one embodiment may be included in another embodiment. Or, it may be replaced with a corresponding configuration or feature of another embodiment. For example, the method described in the second embodiment below may be applied to the method described in the first embodiment, and vice versa.

  First, we will see how the terminal performs group measurements. Here, the group measurement may refer to a measurement procedure performed for management (ie, group management) of the terminals belonging to the terminal group. In other words, group measurement may correspond to one of the procedures for group management.

  For example, the measurement of a group refers to a procedure in which a terminal and / or a base station or the like monitors the connectivity (ie, link state) between terminals in order to ascertain the state of the terminal belonging to the group. obtain.

  At this time, the measurement procedure of the group described above is performed by a signal defined in advance (eg, a discovery signal) or a measurement signal (measurement signal) set only for the group measurement. Example: It may be performed by a side link measurement signal, and a specific resource may be separately set for the above-described group measurement procedure.

  Hereinafter, 1) resource setting method, 2) transmission method of the measurement signal, and 3) relay method of the measurement signal regarding the measurement procedure of the above-described group will be specifically described.

First Embodiment—Method of Setting Resource Area for Group Measurement

  In the first embodiment, a method of setting a resource area used for performing group measurement between terminals will be described.

  A resource region for the above group measurement may be defined (or set) as follows. Here, the resource area refers to a specific range of resources, and may be referred to as a resource pool.

  First, a resource region for group measurement may be set to an uplink resource region (UL resource region) used in the existing LTE system. For example, an LTE (WAN) UL region and a region divided into TDM in an UL spectrum may be separately allocated for group measurement. The corresponding scheme may be efficient when the group is measured using a network assisted scheme such as a base station.

  Alternatively, the resource area for group measurement may be set to an existing side link resource area. In this case, the existing side link resource area corresponds to a side link discovery area, a side link SA (Scheduling Assignment) and / or a data area, or a resource area separately set for group measurement. obtain.

  For example, a sidelink discovery area may be used for group measurements. This is similar to an existing discovery signal (eg, a D2D discovery signal) in that a measurement signal used for group measurement is used for determining the presence of a terminal and characteristics of a service (and / or signal). This is because there are times.

  As another example, the sidelink SA and / or data area may be used for group measurements. In some cases, the resource area for transmitting the above-described measurement signal should be scheduled between terminals without assistance from a network (eg, a base station). Also, when specific information (ie, information related to group measurement) is included in the measurement signal, a large amount of resources may be required, and thus the side link SA and / or the data area is used for group measurement. May be preferred.

  As another example, a separate side link resource area may be set for group measurement. In this case, the separate side link resource area may be referred to as a side link group discovery area. A method of setting a separate resource region for resource scheduling between terminals performing group communication while avoiding interference with terminals not performing group communication may be efficient. In this case, the set additional resource area may be set to be used for transmitting / receiving a signal for group management.

  Also, it is necessary to consider a method of defining the resource area used by each group within the area for group measurement set as described above (that is, the area for group management). That is, the resource area set for the measurement of the group can be divided into groups.

  FIG. 7 shows an example of a resource area configuration for group management to which the method proposed in this specification can be applied. FIG. 7 is for convenience of explanation only and does not limit the scope of the present invention.

  Referring to FIG. 7, resources (eg, a time axis resource, a unit of a subframe, etc.) constituting a resource area for an entire resource area (ie, a resource pool) and an individual group are illustrated as being adjacent to each other. However, the present invention is not limited to this, and may be set so as not to be adjacent to each other. That is, FIG. 7 is an example in which the corresponding resource (or resource area) is logically displayed.

  When the resource area for managing the groups as described above is set as shown in FIG. 7, the resource area for each group may occupy a part of the entire area. At this time, a terminal supporting the group communication (that is, capable of performing the group transmission service) may be preset with information on the configuration of the resource area as shown in FIG. Alternatively, the corresponding terminal may transmit the information through higher layer signaling by a base station (or a network) or the like and / or a physical channel.

  For example, the terminal receives information about the resource pool for group measurement from the base station, and indicates a sub-resource pool for the group to which the terminal belongs in the received resource pool. Information may be additionally received. Alternatively, if the terminal has already set up a resource pool for group measurement, the terminal may receive only information indicating a sub-resource pool for the group to which the terminal belongs.

  In the case of communication with high mobility of the terminal (for example, communication for a vehicle such as V2V and / or V2X), a situation of handover or out-of-coverage may frequently occur. At this time, a terminal that performs (or intends to perform) group communication is likely to experience such a situation as well.

  Therefore, in order for the terminal to prepare for a handover operation or the like, or to perform a group transmission service between terminals belonging to out-of-coverage, the terminal basically (ie, default) falls back. A method of allocating a resource region for a fall-back mode may be considered. Here, the resource region for fallback mode may refer to a resource region set to be used when a terminal cannot receive resource allocation from a base station for transmission and reception of a specific message.

  In this case, the terminal can be preset with information on the resource area for fallback mode, and all terminals supporting group communication receive the corresponding information in the same or semi-static manner. It can be set as follows.

  If the terminal desires to create a new group, the terminal may select a resource area (eg, a sub-resource area) for the corresponding group via the resource area as shown in FIG.

  For example, if the terminal can receive network support (or assistance) while connected to the base station (eg, D2D mode 1 or V2X mode 3), the terminal transmits information indicating a serving resource area to be used to the base station. It can be transmitted from a station or the like.

  In another example, when the terminal has to directly select a resource (eg, D2D mode 2 or V2X mode 4), the terminal calculates through a sensing operation on a resource area for group communication. The value may be used to select a particular resource area. Specifically, it is assumed that the terminal performs a sensing operation on the resource area for a predetermined period. At this time, the UE may select a resource region having the lowest received energy among sub-resource regions having energy equal to or less than a specific threshold value (eg, a first threshold value).

  In this case, the above-described sensing operation and energy detection may be performed in all the regions within the corresponding resource region, or may be performed only in a part of the region that is determined to be used for signal transmission. Alternatively, the above-described sensing operation and energy detection may be performed only for a region where the head terminal transmits a signal (eg, the first TTI of each resource region) or a region where the highest energy is detected. is there.

  If the reception energies of all the sub-resource areas are equal to or greater than the threshold value, the UE selects a resource area with the lowest reception energy among sub-resource areas having different threshold values (eg, a second threshold value). , May be set to select at random. The above-mentioned threshold values (eg, the first threshold value and the second threshold value) may be predefined in the system or signaled via an upper layer and / or a physical channel. For example, the second threshold value may be greater than or greater than the first threshold value.

  As another example, when the terminal has to directly select a resource, the terminal may select a specific resource region using a CBR (Channel Busy Ratio) for a resource region for group communication. . Here, CBR refers to a ratio of resources in which a signal level above a certain threshold value is detected during a certain section observed (or monitored) by a terminal. Specifically, the UE may measure a CBR value for a resource region for group communication and select a sub-resource region having the lowest CBR value.

  In addition, transmission of a signal (eg, transmission of a measurement signal) in the resource region described above may be periodically transmitted to indicate a connection state of each terminal. At this time, in the case of the above-described energy detection method or CBR value measurement method, the state of the sub-resource area selected according to time may be reduced (eg, increase in interference, increase in resource usage, etc.).

  Therefore, the resource area for each group can be reselected or updated at regular intervals. Such reselection or update may be performed by a specific terminal belonging to the group (eg, the leading terminal), and the result of the reselection or update may be reported to another terminal (eg, the following terminal). Through this, all the terminals belonging to the group can reselect the sub-resource area together. However, for this reason, all terminals belonging to the group need to share the corresponding information (that is, information on the result of the reselection or update) in the same manner.

  For example, a method of displaying a counter (or a timer) indicating a valid period of a corresponding signal in a partial field of the measurement signal may be considered. Also, before the corresponding counter expires, a specific terminal (eg, a leading terminal) may transmit information on a sub-resource area to be reselected to the remaining terminals.

  After the terminal of the corresponding group reselects the sub-resource area, the terminal may transmit the measurement signal in the same manner as operating in the previous (ie, before the reselection) sub-resource area. At this time, only the first terminal may transmit the measurement signal, or all terminals (that is, the first terminal and (partly or all) following terminals) may transmit the measurement signal.

  However, if the terminal belonging to the group has not received the reselection (or update) information of the sub-resource area, the terminal cannot participate in the group in succession. Therefore, before the reselection occurs and / or even after the reselection occurs, a specific terminal (eg, a head terminal) transmits a measurement signal or a signal corresponding thereto using a specific resource area to form a group. Can be considered.

  FIG. 8 shows another example of a resource area configuration for group management to which the method proposed in this specification can be applied. FIG. 8 is for convenience of explanation only and does not limit the scope of the present invention.

  Referring to FIG. 8, it is assumed that some of the resource areas set for group management are set for a fallback mode.

  For example, a specific terminal may be configured to transmit a measurement signal in a resource region set for fallback mode use in case a terminal belonging to the group has not received the reselection information described above. . At this time, the measurement signal is a duplicate signal of an existing signal to be transmitted, is partially modified, and / or necessary information (eg, information on a sub-resource area to be reselected). May be the added signal. Here, the specific terminal may correspond to a head terminal of each group, that is, a head terminal in a sub-resource area corresponding to each group.

  Specifically, a terminal transmitting a measurement signal in the first sub-resource area (Sub-resource pool # 0) may additionally transmit a measurement signal in a resource area for a fallback mode that is separately set. Similarly, a terminal transmitting a measurement signal in the second sub-resource area (Sub-resource pool # 1) may additionally transmit a measurement signal in a resource area for a separately set fallback mode. , And the third sub-resource area (Sub-resource pool # 2). In other words, a specific terminal (eg, a leading terminal) belonging to each group may be set to transmit an additional signal in a separately set resource region.

  At this time, the resource area for the fallback mode may be predefined on the system or semi-statically set through upper layer signaling. Further, the signal transmitted in the resource region in the fallback mode may be set to be transmitted from a time point of n * P to a time point of m * P after the occurrence of the reselection before the reselection occurs. Here, P indicates a transmission period of the measurement signal, and n and m may indicate non-negative integers.

Second Embodiment-Signal Transmission Method for Group Measurement

  Next, in the second embodiment, a method of transmitting a signal (eg, a measurement signal) for measuring a group between terminals will be described.

  For example, it is assumed that a specific terminal (eg, a leading terminal) attempts to activate a group transmission service in a specific resource region (eg, a sub-resource region in which detected reception energy is equal to or less than a second threshold). I do. In this case, the terminal needs to first confirm that no terminal has transmitted a measurement signal for transmitting a group in the corresponding resource area. Thereafter, the terminal may be configured to transmit the measurement signal at a specific position (or a randomly set position) in the corresponding resource area.

  For example, the terminal may transmit the measurement signal in the first resource region of the corresponding resource region (ie, the selected (or set) sub-resource region). In this case, the other terminals belonging to the group are set to transmit the measurement signal through the resource following the first resource area, or directly transmit the specific signal through the sensing operation or the like. Sometimes you choose. Alternatively, the head terminal and / or the base station may designate resources used by other terminals belonging to the group, and the order of resources used may be defined (or set) in advance.

  FIG. 9 illustrates an example of a resource allocation method for signals for group measurement to which the method proposed in this specification can be applied. FIG. 9 is for convenience of explanation only and does not limit the scope of the present invention.

  Referring to FIG. 9, it is assumed that a resource area for managing a group is set, and the resource area is divided into sub-resource areas for each group. Hereinafter, the description related to FIG. 9 relates to a terminal operation performed in a specific sub-resource area allocated to a specific group.

  A specific sub-resource area may be configured with n resources (eg, resource # 0 to resource # (n-1)). At this time, the position of the resource to which the following terminal transmits the measurement signal can be set (or assigned) by the first terminal.

  In this case, the head terminal may receive information on the resource area and / or the sub-resource area from the base station, and may use the received information to set resources used by the following terminal. That is, the head terminal can allocate the resources of the following terminal by a network assisted (or network instruction) method.

  Specifically, the first terminal belonging to each sub-resource area may be set to transmit a measurement signal using the first resource (resource # 0) of the corresponding sub-resource area. Also, the head terminal can allocate resources used for transmitting the measurement signal to other terminals belonging to the group (eg, following terminal # 0, following terminal # 1).

  For example, the following terminal # 0 transmits the measurement signal using the second resource (resource # 1), and the following terminal # 1 transmits the measurement signal using the third resource (resource # 2). Can be set to At this time, the resource area used by the following terminal may be set continuously or discontinuously.

  Further, the leading terminal and the follow-up terminal need to be set so as to recognize (or identify and grasp) the characteristic possessed by the specific terminal using the above-described measurement signal. Furthermore, a terminal desiring to belong to the corresponding group must be able to acquire information on a service type, a group type, and the like using a measurement signal transmitted by a terminal belonging to the group. In addition, the connectivity of the terminals belonging to the group can be confirmed through information on not only the signal quality but also the actual position of the terminals and / or the distance between the terminals.

  In view of such a point, the above-described measurement signal may include the following information (or may be mapped). At this time, the information may be included in each field of the measurement signal, or another type of information may be included in one field.

  First, the measurement signal may include service identifier (service ID) information (eg, 6-bit information). The information of the service identifier can be used to confirm whether or not the terminal corresponds to a transmission service of a group in which the terminal desires the service via the measurement signal (that is, a service performed through the group communication). However, when the transmission service of the group uses a specific resource area alone, the service type can be determined implicitly without the information of the service identifier. Therefore, the information of the service identifier may not be included. Can be selective.

  In addition, the measurement signal may include information (eg, 16-bit information) of a group identifier (group ID). The information of the group identifier can be used by a terminal desiring to belong to a specific group to identify the corresponding group. The information of the group identifier may be generated together with the head terminal while generating the group, or may be assigned by the base station or the like.

  Further, the measurement signal may include information of a cell identifier (cell ID) (eg, 9-bit information) including the measurement signal. When the transmission service of a group is signaled from a network or the like, it may be preferable that all terminals belonging to the same group belong to the same base station (or cell). Accordingly, cell identifier information may be included in order to check which cell the corresponding group belongs to. As an example, terminals belonging to a group may transmit cell location information and the like from a base station, a leading terminal, and / or another following terminal while connecting to a specific cell. Alternatively, in a resource area operating in out-of-coverage, cell identifier information may not be necessary.

  Further, the measurement signal may include information on an order within a group (eg, 3-bit information). The information on the order within the group may be used to confirm the order in which the following terminal belongs to the group. The size of the field to which the corresponding information belongs may be related to the number of resources constituting the sub-resource area (eg, n in FIG. 9). As an example, if the maximum number of terminals (leading terminal and following terminal) that can belong to a specific group is n, each sub-resource area can be configured with a maximum of n resources. In this case, the information (or field) indicating the order in the group can be represented by the maximum ceil (log2 (n)). Here, ceil (x) means an operation of rounding up the decimal part of x.

  In addition, the measurement signal may include information of a terminal identifier (UE ID) (eg, 16-bit information). The information on the terminal identifier of the measurement signal may mean an identifier of a terminal transmitting the corresponding measurement signal. However, when the above-described information of the group identifier and the information of the order within the group are included in the measurement signal, or when a certain terminal can be specified through certain conditions, the information of the terminal identifier may not be included in the measurement signal. is there.

  Also, the measurement signal may include location information of the terminal. The terminal can determine whether the terminal belongs to the group or whether a problem has occurred based on the location information of the terminal as well as the method of measuring the link quality using the measurement signal.

  For example, when a condition that the interval between terminals must be maintained within a certain value is set, a specific terminal (eg, a leading terminal) is provided with a terminal position so that the corresponding condition can be satisfied. Information may be signaled. In particular, if all terminals belonging to a specific group are connected to the same cell (or RSU capable of signaling the corresponding group) and have the location information of the corresponding cell, only the relative position from the cell is transmitted. In some cases, the size of the terminal location information may be reduced.

  Specifically, when the interval between base stations (that is, ISD) is 1.732 km, the terminal has a range of about +/- 1 * ISD and can move in the x-axis and y-axis directions. Assume. In this case, when the distance between the lanes is 3 m and the resolution for the position information is a smaller value (eg, 2 m), it is represented by 11-bit information on each of the x-axis and the y-axis. (Ie, a total of 22 bits).

  On the other hand, when a terminal belonging to a group is not connected to a specific cell (or RSU or the like) in an environment such as out-of-coverage, and there is no point set as a reference point (reference) of location information, Transmission of relative position information as described above may not be possible. In this case, the position information of the terminal may be transmitted using a larger number of bits, or the position information of the terminal may not be included in the measurement signal.

  In addition, the measurement signal may include timer (or counter) information indicating a validity (or a valid section) of the measurement signal. In this case, the corresponding information can be operated (or started) from the time when the measurement signal is transmitted. Alternatively, the corresponding information may be used to notify a remaining valid time when a specific terminal (eg, a leading terminal) attempts to change a resource for transmitting a measurement signal.

  If the timer value included in the corresponding information expires and there is no further signaling or the like, the terminal may be set to automatically reselect resources. However, if the terminal does not intend to reselect resources, the terminal may reset the corresponding timer or change the timer to a specific value before expiration and transmit the measurement signal.

  Also, when the terminal desires to belong to the already generated group, the base station (or the network) may be instructed to belong to the group in the same manner as described above, or the terminal may directly perform the sensing operation or the like. May belong to a group.

  For example, if the terminal can be supported by the network while being connected to the base station (eg, D2D mode 1 or V2X mode 3), the terminal may list an operating group (ie, a group list) and / or a corresponding list. Information for a group can be transmitted from a base station or the like.

  As another example, if the terminal should directly select a group (eg, D2D mode 2 or V2X mode 4), the terminal uses the value calculated through the sensing operation on the resource area for group communication. , A particular resource area may be selected. Specifically, it is assumed that the terminal performs a sensing operation on the resource area for a predetermined period. At this time, the terminal may identify a group having energy equal to or less than a specific threshold value (eg, a first threshold value).

  In this case, the above-described sensing operation and energy detection may be performed in all the regions within the corresponding resource region, or may be performed only in a part of the region that is identified as being used for signal transmission. Alternatively, the above-described sensing operation and energy detection may be performed only in an area where the head terminal transmits a signal (eg, the first TTI of each resource area) or an area where the highest energy is detected. Good.

  In addition, the terminal may obtain information on a group through demodulation of a specific area or a plurality of areas in the resource area. Further, when the terminal desires to belong to the group, the group joining procedure may be performed through a request message (eg, a group join request) transmitted by the base station or the like. This is possible when the terminal uses a head terminal and / or a support scheme via a network.

  Also, if the reception energies of all the sub-resource areas are equal to or less than the above-described threshold value (eg, threshold value 1), the terminal may recognize that there is no transmission service of the currently available group in the vicinity. In this case, the terminal may wait for a certain period of time and attempt to subscribe to the group transmission service again, or activate the transmission service of the group desired by the terminal. If the corresponding terminal activates the transmission service of the group, the corresponding terminal can play the role of the first terminal of the group.

Third Embodiment-Signal relay operation method for group measurement

  Next, in a third embodiment, a method of relaying a signal for the above-described group communication (eg, group transmission) will be described.

  When group communication is used, a specific terminal can grasp the existence of adjacent terminals, but it may be difficult to always grasp the presence of all terminals belonging to the group. As an example, if only the first terminal in a group transmits a measurement signal and the remaining terminals (eg, following terminals) receive only the measurement signal (ie, a signal measurement signal transmitted directly from the first terminal), A terminal that cannot receive the measurement signal may occur.

  Therefore, in receiving a measurement signal or the like, a method of receiving a signal from an adjacent terminal and maintaining transmission of a group instead of receiving a signal only from a specific terminal (eg, a leading terminal) may be considered. . In other words, the first tracking terminal can receive the measurement signal transmitted from the head terminal and transmit it to the second tracking terminal (ie, relay the measurement signal). In this case, the first tracking terminal may be set as a relay terminal.

  At this time, the terminal that performs the above-described relay operation may be set as follows.

  For example, all terminals belonging to the group may be set to relay the measurement signal. This is a method in which all the terminals relay the received measurement signal, instead of the terminal determining whether or not to relay according to a specific criterion.

  As another example, a terminal whose received measurement signal level is higher than a certain threshold value may be set to relay the measurement signal. In other words, only when the quality of a signal received from a specific terminal (eg, the first terminal) is sufficiently good, the terminal may transmit the corresponding signal as it is (or change some information) to another terminal. is there. Through this, a terminal having a poor quality of a signal received from a specific terminal may have an opportunity to receive a relay signal from a neighboring terminal.

  At this time, the terminal compares the signal quality of the direct link (that is, the link with the head terminal) and the signal quality of the relay link (that is, the link with the adjacent relay terminal), and obtains a higher quality signal. The signal may be regarded as a measurement signal to determine whether to maintain the group. However, a terminal in which both the quality of the signal directly received from a specific terminal (eg, the leading terminal) and the quality of the signal received through the relay operation are incompatible, cannot receive the transmission service of the corresponding group.

  As another example, a terminal whose received measurement signal level is lower than a certain threshold value may be set to relay the measurement signal. Through this, it is possible to restrict that a large number of terminals within the coverage of a signal transmitted by the first terminal perform a relay operation. That is, the terminal may perform a relay operation for coverage extension when the quality of a signal received from a specific terminal (eg, the leading terminal) is not sufficiently good. However, also in this case, the quality of the received signal needs to be equal to or higher than the level at which the minimum decoding can be performed.

  The relay operation described above may be performed only one hop (1 hop) or may be maintained for n hops (n-hop). The setting for this may be predefined on the system or signaled via higher layers and / or physical channels or the like.

  FIG. 10 illustrates an example of a signal relay operation for measuring a group to which the method proposed herein can be applied. FIG. 10 is for convenience of explanation only and does not limit the scope of the present invention.

  Referring to FIG. 10, it is assumed that a resource area for managing a group is set, and the corresponding resource area is divided into sub-resource areas for each group.

  For example, the first terminal of the corresponding group may transmit the measurement signal using the first resource (resource # 0) of the specific sub-resource area. In other words, the first resource may mean a resource corresponding to a direct link related to transmission of the measurement signal.

  A terminal that immediately performs a relay operation on a measurement signal transmitted using the first resource may transmit the corresponding signal using the second resource (resource # 1). In this case, the signal transmitted on the second resource may be referred to as a 1-hop relay signal.

  Also, a terminal that performs a relay operation on a measurement signal transmitted using the second resource may transmit the corresponding signal using the third resource (resource # 2). In this case, the signal transmitted by the third resource may be referred to as a 2-hop relay signal.

  Similarly, a signal transmitted on the n-th resource via the n-th relay operation may be referred to as an (n-1) -hop relay signal.

  FIG. 11 illustrates an example of signaling between a base station and a terminal performing side link communication to which the method proposed in this specification can be applied. FIG. 11 is for convenience of explanation only and does not limit the scope of the present invention.

  Referring to FIG. 11, it is expected that the base station and the terminal can perform the operations described in the first to third embodiments described above. Also, the resource pool described in FIG. 11 may mean a resource area (ie, a fixed time and / or frequency resource area). In addition, the first terminal may refer to the leading terminal (leading UE) (or a relay terminal) described above, and the second terminal may refer to the following terminal (following UE) (or a remote terminal) described above.

  In operation S1105, the first terminal (and the second terminal) may receive the resource pool allocation information. Here, the resource pool allocation information may mean information indicating at least one resource pool among a plurality of preset resource pools.

  In operation S1110, the first terminal may identify a specific sidelink resource for the second terminal in the at least one resource pool. Here, the specific side link resource is a signal for performing a side link measurement (e.g., group measurement) between the first terminal and the second terminal (e.g., a measurement signal (e.g., a measurement signal). measurement signal)). For example, as shown in FIG. 9, the first terminal may identify (or select) resource # 1 or resource # 2 for the second terminal among n resources included in the resource pool.

  In operation S1115, the first terminal may transmit a signal (or a message or information) for allocating the identified specific side link resource to the second terminal.

  Thereafter, the second terminal may transmit a signal using a specific side link resource allocated by the first terminal. In other words, the first terminal may be configured to allocate (or control) resources used by the second terminal to transmit and receive a specific signal in a resource pool allocated by the base station.

  That is, the first terminal may allocate the resources of the second terminal according to the network support (or instruction) method.

  In this case, the at least one resource pool may be allocated for a specific terminal group to which the first terminal and the second terminal belong (ie, a terminal group providing a specific group service).

  In addition, the signal for performing the side link measurement includes identification information of a specific terminal group (eg, a group identifier) or terminal order information within a specific terminal group (eg, order information within a group). It may include at least one.

  In addition, the specific side link resource is identified according to a resource order set for the second terminal, and the resource order is determined based on a preset resource pattern. Can be set.

  The preset plurality of resource pools may include one or more sub-resource pools set for each terminal group, and the resource pool allocation information may be received via higher layer signaling.

  Also, the signal for performing the side link measurement may include a counter (or a timer) indicating the validity of the signal. At this time, before the counter expires, the first terminal may transmit information indicating a new resource pool for transmitting a signal for performing the side link measurement to the second terminal. At this time, the new resource pool may be one of the preset plurality of resource pools.

  The specific side link resource is at least one of a received signal energy value or a CBR value measured for one or more side link resources constituting the at least one resource pool. Can be determined using

  Also, as shown in FIG. 8, the preset multiple resource pools may include a specific resource pool for a fall-back operation associated with the measurement of the side link. . In this case, the first terminal (eg, the leading terminal) may be configured to (additionally) transmit a signal for performing the side link measurement in the specific resource pool.

  Next, a method of performing terminal synchronization that may be considered when performing the above-described group communication will be described.

  When terminals perform group communication, in order for signals to be normally transmitted and received between terminals belonging to the corresponding group, each terminal needs to have a predetermined timing (or frequency) or the same synchronization. It is necessary to have a synchronization reference. Here, the synchronization reference may refer to the time of the synchronization reference and / or the frequency of the synchronization reference.

  Although the method proposed herein is described in terms of the timing of the synchronization reference, this is for convenience of description only and may be applied to the frequency of the synchronization reference as well. Of course.

  Hereinafter, a specific description will be given of 1) a priority setting method at the time of the synchronization reference and 2) a relay method of the synchronization signal regarding the synchronization in the group communication.

Fourth Embodiment-Method of setting priority of synchronization reference in group communication

  First, a method of setting the priority of a synchronization reference (eg, the time of the synchronization reference) when the terminal performs group communication will be described.

  A terminal that performs group communication within a specific group (and / or a terminal that performs a relay operation) is generally located within a certain coverage from a specific terminal (eg, a leading terminal). In other words, there is a high possibility that the terminals belonging to the corresponding group exist at geographically close positions.

  Therefore, the terminals belonging to the group are likely to belong to the same network (eg, base station, cell, etc.), and aspects such as signal quality and / or signal delay received from the corresponding base station, etc. But sometimes the similarity is high.

  However, if all (or some) terminals belonging to the corresponding group move, any of the moving terminals may experience network changes such as handover.

  Therefore, it may not be preferable to determine information transmitted from a base station or the like as a criterion for maintaining a group. Also, when the terminal moves, information such as the GNSS time (Global Navigation Satellite System timing) can of course also vary according to the mobility of the terminal.

  Therefore, it is preferable that a terminal performing group communication considers a separately set group synchronization signal (group synchronization signal) as a reference time point, rather than a reference time point that may fluctuate or be inaccurate. There is. Here, the reference time that may be incorrect may refer to a reference time that may cause a synchronization mismatch between terminals belonging to the group.

  For example, when performing group communication (ie, transmitting and receiving) in the side link area, a synchronization signal (ie, SLSS) for group communication (ie, group transmission service) defined separately from other side link communication. (Sidelink Synchronization Signal)) or the like may be considered.

  In this case, the identifier information of the SLSS for the group communication (or the relay operation related to the group communication) and the like can be transmitted to the terminals belonging to the group through a predefined physical channel or dedicated signaling (dedicated signaling). For example, the physical channel may correspond to PSDCH, PSCCH, PSSCH, and the like. Also, the identifier information and the like may be transmitted to a remote terminal that performs a relay operation.

  At this time, the synchronization signal for group communication can be set to the highest priority. That is, even when a terminal belonging to the group can receive a synchronization signal from the base station, the synchronization signal (ie, SLSS) transmitted by another terminal belonging to the group (eg, the head terminal) is synchronized with the synchronization reference. Signal.

  Also, when a terminal moves within a cell of a cellular environment or between cells, the synchronization point of the base station may continuously change according to the movement of the terminal (eg, a terminal belonging to a group). In this case, since the change amount is related to the change amount of the distance to the base station, the change amount may be larger than the change amount at the time of synchronization of the GNSS. However, in order to allow an operation such as rejoining the group after the terminal leaves the group at any time, it is advantageous that the synchronization acquisition time is as short as possible.

  Therefore, when the synchronization signal for the group communication is not used, it may be preferable that the terminal performs the group communication according to the synchronization time of the base station rather than the synchronization time of the GNSS.

  That is, a terminal that performs group communication in the side link area has one rank of the SLSS (or an equivalent SLSS) for the group communication and two ranks of the base station synchronization signal (or the synchronization signal equivalent thereto). , The synchronization signal of the GNSS is set to three ranks, and the time point of the synchronization reference can be set.

  In other words, a terminal that wants to join a specific group first determines the presence or absence of the group and / or obtains group-related information (eg, information on a group identifier, etc.) by using the above-described priority order first. Synchronization may be performed according to (priority).

  Also, if the SLSS for group communication is not detected, the terminal detects the synchronization signal of the base station and sets the connection to the base station, and then performs group communication (eg, group communication with an existing generated group). For persistent attempts, signaling may be performed with the base station. Alternatively, the corresponding terminal may generate a synchronization signal (that is, a group synchronization signal) for group communication independently (or based on the synchronization time of the base station) and start a new group communication operation. is there.

  In addition, when not only the SLSS for group communication but also the synchronization signal of the base station is not detected, the terminal may detect the synchronization signal of the GNSS and set this to the time of the synchronization reference. Through this, the terminal communicates with the out-of-coverage terminal, or generates a synchronization signal for independent group communication (or based on the synchronization time of the GNSS) and generates a new group communication. Operation may be started.

  When following the search order at the time point of the synchronization reference, the other terminals of the group (eg, a follow-up terminal, a remote terminal, etc.) perform SLSS for group communication to perform group communication, a synchronization signal of a base station, The search for the synchronization signal can be prioritized in the order of the GNSS synchronization signal and the like.

  At this time, there is no need for terminals belonging to the group to search for SLSS or the like of another group as a representative terminal (or relay terminal), and signals, messages, and / or signals for group communication directly from the network (or base station). Alternatively, the case of exchanging data or the like may be considered. In this case, the SLSS for the group communication may be the SLSS that the representative terminal transmits to itself, or may be set to a signal that does not need to be searched, among the synchronization reference times. That is, among the synchronization signals for group communication, the synchronization signal of the base station is set to one rank, and the synchronization signal of the GNSS and the like may be in the next order. In other words, the representative terminal (i.e., the relay terminal) may be set to follow the time of synchronization by the synchronization signal of the base station when there is no need to follow the SLSS of another terminal.

  In addition, in addition to the above-described method, the order of selecting a synchronization source may change according to the service type of a data packet transmitted and received by the terminal. Here, the synchronization source may refer to an entity that the terminal can refer to when performing synchronization.

  That is, the priority of the synchronization signal of the base station may be set higher than the priority of SLSS. As an example, in a relay operation, if the remote terminal receives all signals, messages, and / or data, etc. related to the relay operation from the relay terminal, the SLSS transmitted from the relay terminal may be higher than other synchronization signals. Can take precedence.

  However, when some signals, messages, and / or data (hereinafter, type 1 messages) related to the relay operation are transmitted only from the base station, the remote terminal may give priority to the synchronization signal of the base station. Similarly, before the remote terminal performs a relay operation with the linked relay terminal or establishes a connection with the relay terminal, the remote terminal receives and tracks the synchronization signal of the base station. Can be set.

  Here, paging, a system information block (SIB), an RRC message, or the like necessary for a relay operation or other operations may correspond to an example of the type 1 message. At this time, the remaining signals (eg, control signals), messages, and / or data related to the relay operation may be referred to as type 2 messages.

  At this time, if the type 2 message follows the SLSS transmission timing of the relay terminal, it may be burdensome for the remote terminal to receive and track the synchronization signal of the base station while receiving and tracking the SLSS signal.

  Accordingly, in such a case, while the synchronization signal of the base station is basically given the highest priority, the reference time of the type 2 message transmitted from the relay terminal to the remote terminal also follows the time of the synchronization signal of the base station. It can be set at the base station (or network). In other words, the remote terminal can be set to synchronize based on the synchronization point of the base station.

  Alternatively, if the period of the type 1 message is much longer than the period of the type 2 message, or the transmission of the type 1 message can occur sufficiently independent and exclusive of the transmission of the type 2 message. It may be determined. For example, paging, system information blocks, RRC messages, etc. may be set to be transmitted in a very long period.

  In this case, before and after the relay operation (or the connection operation between the relay terminal and the remote terminal for the relay operation), the remote terminal selectively receives and tracks the synchronization signal and the SLSS of the base station as needed. May be set to That is, the base station (or the network) may set the remote terminal to perform the receiving and tracking operation of the synchronization signal of the base station and the receiving and tracking operation of the SLSS signal by switching.

  Also, when data to be transmitted by a specific terminal (that is, a data packet) occurs, the corresponding terminal needs to determine a point in time when the corresponding data is transmitted. At this time, if the terminal (and the receiving terminal) implicitly knows the service type of the data, the synchronization source may be determined according to the service type of the data.

  Alternatively, the transmitting terminal and / or the receiving terminal may explicitly indicate the relevant data or a specific control channel (or RRC signaling) associated with the relevant data, for example. As an example, the terminal maps the corresponding data to a partial field of a control channel (eg, PDCCH) for scheduling (eg, a ProSe packet priority (PPPP) field of DCI, a service ID field, a configuration index field, etc.) and transmits. I can do it.

  More specifically, the type of the service (and the order of the synchronization source according to the service) may be based on data priority (eg, PPPP), source (source), destination ID, and / or logical channel index (logical channel). index) or the like. For example, the terminal may be configured to scan an SLSS for group communication, a base station synchronization signal, a GNSS synchronization signal, an ISS (Independent Synchronization source), and the like. In this case, when the PPPP values for the data exchanged by the terminal are given from 0 to 7, the priority values that each synchronization source will have according to the specific PPPP value may be represented as shown in Table 3.

  Table 3 is just one example, and the range of the PPPP value can be subdivided and changed to a different value depending on the priority of the synchronization source. The mapping relationship shown in Table 3 may be predefined on the system, semi-statically set via higher layer signaling, or signaled via a physical channel or the like.

  In addition, according to the identifier of the source terminal (that is, the terminal that transmits data) and / or the identifier of the destination terminal (that is, the terminal that receives data and the target terminal), the type of service (and thus the synchronization source Are determined, the following method can be considered. As an example, in group communication, a source terminal may mean a relay terminal and a destination terminal may mean a remote terminal.

  First, the type of service and the order of synchronization sources according to the service type may be determined according to the identifier value of the source terminal (method 1). Specifically, when the identifier of the target terminal is not limited to only one or a plurality of values (that is, when an unspecified number of terminals can receive data for a specific service), the corresponding service is determined according to the identifier value of the source terminal. And / or the order of the synchronization sources may be determined.

  For example, the type of the service and / or the order of the synchronization sources may be determined according to the range of the identifier value of the source terminal. At this time, the relationship of the mapping to the order of the synchronization source according to the range of the identifier value of the source terminal may be predefined on the system, determined semi-statically via higher layer signaling, etc. And so on.

  As another example, the type of the service and / or the order of the synchronization sources may be determined according to what category (ie, the category of the terminal) the identifier of the source terminal belongs to. At this time, the relationship between the category related to the identifier of the source terminal and the mapping to the order of the synchronization source may be predefined on the system, semi-statically determined through higher-layer signaling or the like, or may be physically determined. It may be signaled via a channel or the like.

  Alternatively, the type of the service and the order of the synchronization sources according to the service type may be determined according to the identifier value of the target terminal (method 2). Unlike the method 1, when the identifier of the source terminal is not limited to only one or a plurality of values (that is, when an unspecified number of terminals can transmit data for a specific service, according to the identifier value of the target terminal, The type of the corresponding service and / or the order of the synchronization source terminal may be determined, and the mapping relationship between the identifier of the target terminal and the type of the service and / or the order of the synchronization source is the same as in the above-described method 1. possible.

  Alternatively, the combination of the identifier value of the source terminal and the identifier value of the target terminal may determine the type of service and the order of the synchronization sources according to the combination (method 3). This corresponds to the case where the type of the corresponding service and / or the order of the synchronization source are determined according to the combination between the specific source terminal and the specific destination terminal. The relationship between the combination between the identifiers and the mapping between the type of service and / or the order of the synchronization source may be the same as in the case of Method 1 described above.

  For example, the type of the service and / or the order of the synchronization sources may be determined by a combination of the range of the identifier value of the source terminal and the range of the identifier value of the destination terminal. At this time, the relationship of the mapping to the order of the synchronization sources by the combination of the identifier value of the source terminal in the specific range and the identifier value of the target terminal in the specific range is predefined on the system or through signaling of the upper layer or the like. May be determined semi-statically or signaled via a physical channel or the like.

  As another example, the type of the service and / or the order of the synchronization sources may be determined according to what category the combination between the identifier value of the source terminal and the identifier value of the destination terminal belongs to. . At this time, the relationship between the category of the combination of the identifier value of the source terminal and the identifier value of the target terminal and the mapping to the order of the synchronization source is predefined on the system or semi-static via upper layer signaling or the like. Or may be signaled via a physical channel or the like.

  In the above-described method, it may be preferable to give priority to SLSS because the operation of the side link is basically targeted because of the characteristics of the service to be used. However, if it is advantageous for the terminal to communicate with the base station (i.e., if it is located very close to the base station), it sends and receives signaling and / or data with the assistance of the base station May be preferred.

  For example, if the reception quality of the base station synchronization signal (ie, downlink synchronization signal) (or a corresponding signal and channel, etc.) is equal to or higher than a certain level, the terminals belonging to the group may synchronize with the base station. The signal may be given priority over other synchronization signals. Alternatively, even if the time resources consumed to maintain downlink synchronization with the corresponding base station or the consumed power is below a certain level, the terminals belonging to the group give priority to the base station synchronization signal. obtain. Here, the consumed time resource may mean a time required to scan a synchronization signal, a time resource required to combine a plurality of synchronization signals over a large number, and the like.

  On the other hand, if the reception quality of the synchronization signal (or corresponding signal and channel, etc.) of the base station is below a certain level, or time resources consumed to maintain downlink synchronization with the corresponding base station (or If (power) is above a certain level, reception of the SLSS may take precedence. Of course, the corresponding SLSS may be transmitted from a specific source terminal or an SLSS related to a combination between a specific source terminal and a specific destination terminal.

  As described above, the priority between the base station and the SLSS may be determined based on the absolute value of the signal quality of the base station, or the signal quality of the base station and the SLSS (or various types of synchronization sources) may be determined. The comparison may determine the order of the synchronization sources.

  Specifically, if it is more advantageous for the terminal to operate according to the time of the base station or to operate with the support method of the base station, the signal quality of the base station is added with an offset of “0” or more. The weight can be increased. Alternatively, when the time point of the ISS is not selected as much as possible, the weight may be reduced by adding an offset of “0” or less to the signal quality of the ISS.

  On the other hand, the signal quality value described above may be set to be effective when the signal quality value is equal to or more than a certain threshold value according to the type of the signal. The above-mentioned offset value and / or threshold value may be predefined on the system, determined semi-statically via higher layer signaling, or signaled via a physical channel or the like.

  In addition, as described above, the priority of the synchronization source may be determined based on the measurement. However, a combination of a specific type of terminal and / or a specific situation may be mapped to the specific synchronization source. A setting method can also be considered. As an example, it is assumed that a specific terminal (eg, a wearable device) receives a service from a relay terminal in a remote terminal mode. In this case, when a specific terminal finds a synchronization source and / or SLSS generated from a specific relay terminal, the corresponding terminal may be set to give priority to the synchronization source over the base station. This may be a setting restricted to terminals operating with a particular service mode or a particular PPPP.

  In addition, the remote terminal does not monitor only the SLSS transmitted by the relay terminal associated with itself or the resource pool including the relevant SLSS, but monitors the resource transmitted from another terminal or group. Monitoring the pool can result in unnecessary power consumption.

  Therefore, in the case of a group performing a relay operation, the remote terminal can be set by the base station to monitor only a specific SLSS or a specific resource pool transmitted by a specific terminal specified by the base station (eg, a relay terminal). . Such a configuration may be conveyed by dedicated signaling such as RRC signaling, or may be dynamically indicated via physical channel signaling.

  Also, if a priority rule is defined so that the SLSS follows the priority order, the indication related to the SLSS resource or the SLSS resource pool indicates that the relay terminal and the remote terminal belong to a specific serving base station together. In this case (eg, in-coverage network), there is no problem. Also, when the remote terminal moves to an adjacent base station, the remote terminal may be set to monitor the SLSS or SLSS resource pool of the existing relay terminal as it is.

  Also, if the relay terminal moves to an adjacent base station (or the relay terminal and the remote terminal simultaneously), before handover to the adjacent base station (or cell), the serving base station may change the SLSS or SLSS of the relay terminal to be changed. Information on the resource pool may be instructed to the relay terminal and the remote terminal. In this case, the relay terminal may be instructed from the adjacent base station for the corresponding setting information. Such a method may be performed by receiving changed setting information from an adjacent base station after the terminal performs handover.

  In particular, when the relay terminal and the remote terminal move to the adjacent base station at the same time, the serving base station (or the adjacent base station after handover to the adjacent base station) is changed before handover to the adjacent base station. Information about the SLSS or SLSS resources of the relay terminal may be indicated to the relay terminal and the remote terminal.

  At this time, if the remote terminal has not received the SLSS of the corresponding group, the remote terminal may directly receive a synchronization signal from a specific relay terminal and / or a base station to which the specific remote terminal belongs. In this case, the remote terminal may receive not only a synchronization signal from the base station but also a signal, a message, and / or data for group communication directly from the base station.

  Also, in this case, the corresponding remote terminal may perform a role of transmitting an SLSS to another terminal as a synchronization reference, and the other terminal transmits (or transmits transmitted) necessary signals, messages, and / or data. Role). In other words, if necessary, the role of the remote terminal can be changed to operate as a relay terminal. Such a role change may be performed by a request of a corresponding remote terminal according to a type of a signal, a message, and / or data to be transmitted, or a type of an application, or may be indicated by a base station.

Fifth Embodiment—Synchronization Reference Time Setting and Communication Execution Method

  Next, a method of setting a time point of a synchronization reference related to the group communication and a method of performing communication between terminals according to the method will be described.

  When performing group communication, a terminal that creates a group (eg, a head terminal) is adjacent to another terminal (eg, a follow-up terminal) that wants to join the group, and can be generally located on the same network (or base station). . Even for a terminal connected to an adjacent cell (eg, a follow-up terminal), the terminal directly performs signaling with a network (or a base station) belonging to the group in order to perform group communication within the group. Or be able to do it indirectly.

  Therefore, a terminal that intends to generate a group (eg, a leading terminal) may apply a synchronization reference time of the base station or a certain offset (eg, t1) to set a reference time of the corresponding group communication. For example, the time point of the synchronization reference of the base station may mean the time point when the terminal receives the synchronization signal from the base station via the downlink.

  The terminal that has set the synchronization reference time in this way can transmit a synchronization signal and data based on the corresponding time while maintaining the group. Just because the corresponding terminal simply moves to the neighboring base station (ie, neighboring cell), does not reselect the corresponding reference time point (ie, synchronization reference).

  Similarly to the above-described method, a terminal that intends to generate a group may apply a GNSS synchronization reference time or a certain offset (eg, t1) to set a reference time of the corresponding group communication.

  At this time, the offset value may be set to a positive value, a real number having a negative value, or “0”. The offset value may be predefined on the system, semi-statically determined via higher layer signaling, or signaled via a physical channel or the like.

  However, when it is determined that using the time of the base station or the GNSS connected initially does not have a significant meaning in the group communication, the specific terminal (eg, the leading terminal) considers the time of another synchronization source. Instead, a unique synchronization point may be set independently.

  Further, when a terminal belonging to a specific group communicates with a terminal of another communication method (eg, a cellular terminal) other than the corresponding group, the terminal may follow a normal synchronization rule (that is, a synchronization priority rule). it can.

  For example, in order to communicate with a terminal that transmits and receives data according to the transmission time of the base station, the terminals belonging to the group can also perform communication after performing synchronization according to the transmission time of the (same) base station. .

  Similarly, when a terminal belonging to a specific group communicates with a terminal belonging to another group, the terminal scans a synchronization signal of an adjacent group other than its own group and communicates with a corresponding synchronization reference time. Need to do. This can be similarly applied when a terminal belonging to a specific group attempts to move to another group.

Sixth Embodiment-Method of Relay Operation of Synchronous Signal Related to Group Communication

  Next, a method in which a terminal relays a synchronization signal related to group communication to another terminal will be described.

  In the case of group communication, at least one terminal in the group needs to transmit a synchronization signal. For example, when the leading terminal transmits a synchronization signal, other terminals located around the leading terminal may receive the synchronization signal.

  However, a case may occur in which some terminals attempting to join the group communication exist outside the coverage of the corresponding group communication, or other terminals (or topographical features) are blocked and the corresponding synchronization signal cannot be received. In particular, in the case of a vehicle terminal (vehicle type UE), the signal may be greatly attenuated because the vehicle is blocked.

  Therefore, for smooth group communication, it may be necessary for another terminal to relay a synchronization signal transmitted by a specific terminal. At this time, instead of all terminals belonging to the group performing a relay operation, a terminal performing a relay operation may be selected by the following method.

Method 1: A method in which all terminals perform a relay operation

  This is a method in which all terminals belonging to a group relay the received measurement signal, instead of determining whether to relay based on a specific reference.

Method 2: A method in which a terminal whose received synchronization signal power is equal to or higher than a certain level performs a relay operation.

  If the quality of the signal received from a specific terminal (eg, the leading terminal) is sufficiently good, the terminal can relay the received signal as it is (or process or change some information) to another terminal. Through this, a terminal having a poor quality of a signal received from a specific terminal may have an opportunity to receive a relay signal from an adjacent terminal.

  Information related to the relay operation described above may be included in a channel (eg, a physical synchronization control channel) that controls information on transmission of a synchronization signal and the like. Here, the information related to the relay operation may include information indicating whether a relay signal is available, a hop counter, a maximum number of hops, and the like.

  At this time, all the terminals may be set to transmit the synchronization signal to the same position. That is, it can be set so that an original signal (eg, a synchronization signal transmitted from a head terminal) and a relay signal are transmitted in the same resource region. At this time, a terminal that transmits a synchronization signal within the group can use an SFN (System Frame Number) scheme. In this case, the coverage of the synchronization signal may be limited by the maximum hop number or the like.

  Alternatively, the original signal, the relay signal, and the relay signal may be set to be transmitted at different positions. A transmission resource may be classified to determine whether a terminal that receives a relay signal can receive a signal directly from a head terminal or a signal that can be received from a relay terminal.

  In this case, a terminal whose original signal and the quality of the relay signal directly received from a specific terminal (eg, the leading terminal) are not good (that is, lower than a certain level) cannot perform the corresponding group communication. That is, the terminal compares the signal quality of the direct link and the signal quality of the relay link, regards the higher quality signal as an actual synchronization signal, and determines whether or not the group is well tracked.

  For example, even if the terminal receives both the original signal and the relay signal, if the original signal is received with higher quality (eg, power above a certain critical value), the terminal will Regardless of its presence, the corresponding synchronization signal (ie, the original signal) can be relayed. Conversely, when the relay signal is received with higher quality, the terminal may transmit the corresponding relay signal at a specific position according to the maximum number of hops of the relay.

Method 3: A method in which a terminal whose received synchronization signal power is below a certain level performs a relay operation.

  In the case of method 2, a case may occur in which a large number of terminals perform the relay operation within the coverage of the signal transmitted by the head terminal. Therefore, in order to limit unnecessary relay operations, a terminal performs a relay operation for extending coverage only when the quality of a signal received from a specific terminal (eg, a leading terminal) is not sufficiently good. How to set can be considered.

  However, also in this case, the received signal needs to be at a level at which decoding of a minimum signal can be performed.

Method 4: Method of performing relay operation by measuring quality of synchronization signal

  This is because, among the synchronization signals received by the terminal, the power of a specific synchronization signal (or a specific type of synchronization signal) is higher than a certain threshold value, and the power of another synchronization signal (or a different type of synchronization signal). Is lower than a certain critical value, the terminal performs a relay operation.

  For example, if a terminal that has received a synchronization signal (eg, a base station synchronization signal, SLSS, etc.) from a relay terminal determines that other terminals can well receive the synchronization signal without a separate relay operation, the remote terminal There is no need to separately relay a synchronization signal or the like.

  In other words, when a terminal that has received SLSS with a quality (e.g., power) above a certain threshold value also receives a synchronization signal of the base station with a quality that is also above a certain threshold value (e.g., when it belongs to in coverage) ), The corresponding terminal can determine that a nearby terminal can search for at least one signal of the base station and / or the SLSS. Therefore, the corresponding terminal does not need to relay the synchronization signal received by itself to a peripheral terminal.

  Similarly, if a terminal that has received the SLSS of a specific group with a quality equal to or higher than a certain threshold value also receives an SLSS of another group with a quality that is equal to or higher than a certain threshold value, the corresponding terminal has a minimum of neighboring terminals. It can be determined that a signal transmitted in at least one of the multiple groups can be searched. Therefore, also in this case, the corresponding terminal does not need to relay the synchronization signal received by itself to peripheral terminals.

  Alternatively, as another example, when a remote terminal receives an SLSS signal from a specific group with a quality equal to or higher than a certain threshold value, and the remote terminal receives a SLSS signal from a specific group (eg, a set base station) or any other In some cases, a synchronization signal having a quality equal to or higher than a certain threshold value cannot be received from the base station. That is, a terminal may receive SLSS in a specific group while being out of coverage from the base station. In this case, the remote terminal may relay its own received SSSS to give other terminals an opportunity to acquire the synchronization signal.

  Similarly, a remote terminal that has received a certain group of SLSS with a quality above a certain threshold may not receive any other group of SLSS with a quality above a certain threshold. . In this case, the remote terminal can judge that any group other than the group to which the peripheral terminal belongs cannot search for the SLSS signal to be transmitted, so that the remote terminal can relay the SLSS received by itself.

  At this time, when a terminal located in the vicinity of the remote terminal receives the relayed SLSS, the corresponding terminal may be of the same type as that in which the received SLSS is set, or transmitted from a communicable (or permitted) group. You can judge whether it was done. Accordingly, the corresponding terminal can determine whether to perform group communication. As an example, the wearable device may be synchronized with other smartphones in the vicinity, or the smartphone may attempt to connect and / or synchronize with other devices.

General equipment to which the present invention can be applied

  FIG. 12 illustrates a block configuration diagram of a wireless communication device to which the method proposed in this specification can be applied.

  Referring to FIG. 12, the wireless communication system includes a base station 1210 and a number of terminals 1220 located within an area of the base station 1210.

  The base station 1210 includes a processor 1211, a memory 1212, and an RF unit (radio frequency unit) 1213. The processor 1211 implements the functions, processes, and / or methods proposed in FIGS. The layer of the wireless interface protocol can be implemented by the processor 1211. The memory 1212 is connected to the processor 1211 and stores various information for driving the processor 1211. The RF unit 1213 is connected to the processor 1211 and transmits and / or receives a radio signal.

  The terminal 1220 includes a processor 1221, a memory 1222, and an RF unit 1223.

  The processor 1221 implements the functions, processes, and / or methods proposed in FIGS. The layer of the wireless interface protocol can be implemented by the processor 1221. The memory 1222 is connected to the processor 1221 and stores various information for driving the processor 1221. The RF unit 1223 is connected to the processor 1221, and transmits and / or receives a radio signal.

  The memories 1212, 1222 may be internal or external to the processors 1211, 1221, and may be coupled to the processors 1211, 1221 by various well-known means.

  For example, in order to transmit and receive downlink data (DL data) in a wireless communication system supporting a low latency service, a terminal may be configured to transmit and receive a radio signal, and a radio frequency (RF) unit may be used. It may include a processor operatively coupled to the unit.

  In addition, the base station 1210 and / or the terminal 1220 may have a single antenna or a multiple antenna.

  FIG. 13 illustrates a block configuration diagram of a communication device according to an embodiment of the present invention.

  In particular, FIG. 13 is a diagram illustrating the terminal of FIG. 12 in more detail.

  Referring to FIG. 13, the terminal includes a processor (or a digital signal processor (DSP) 1310), an RF module (RF module) (or an RF unit) 1335, a power management module (power management module) 1305, and an antenna (antenna). ) 1340, battery 1355, display 1315, keypad 1320, memory 1330, SIM card (Subscriber Identification Module card) 1325 (this configuration is optional), Speaker 1345 and microphone (micro) hone) may be configured to include a 1350. terminal may also include a single antenna or multiple antennas.

  The processor 1310 implements the functions, processes, and / or methods proposed in FIGS. The layer of the wireless interface protocol can be implemented by the processor 1310.

  The memory 1330 is connected to the processor 1310 and stores information related to the operation of the processor 1310. Memory 1330 may be internal or external to processor 1310, and may be coupled to processor 1310 by various well-known means.

  The user inputs command information such as a telephone number by pressing (or touching) a button on the keypad 1320, or by voice activation using the microphone 1350. Processor 1310 receives such instruction information and processes it to perform the appropriate function, such as calling a telephone number. Operational data can be extracted from the SIM card 1325 or the memory 1330. In addition, the processor 1310 may display command information or driving information on the display 1315 for the user's recognition and convenience.

  The RF module 1335 is connected to the processor 1310 and transmits and / or receives an RF signal. The processor 1310 transmits command information to the RF module 1335 to start communication, for example, to transmit a wireless signal that constitutes voice communication data. The RF module 1335 includes a receiver and a transmitter for receiving and transmitting a wireless signal. The antenna 1340 functions to transmit and receive a radio signal. When receiving a wireless signal, the RF module 1335 may transmit the signal for processing by the processor 1310 and convert the signal to a baseband. The processed signal may be converted to audible or readable information output via speaker 1345.

  In the above-described embodiment, the components and features of the present invention are combined in a predetermined form. Each component or feature must be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. Further, it is also possible to combine some components and / or features to constitute an embodiment of the present invention. The order of the operations described in the embodiments of the present invention can be changed. Some components or features of one embodiment can be included in another embodiment or can be replaced with corresponding components or features of another embodiment. Obviously, it is possible to combine the claims having no explicit reference in the claims to form an embodiment, or to include them in a new claim by amendment after filing the application.

  Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, one embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), and digital signal processors (DSPDs). It can be implemented by FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

  In the case of implementation using firmware or software, an embodiment of the present invention can be implemented in the form of a module, a procedure, a function, or the like that performs the functions or operations described above. The software code is stored in a memory and can be driven by a processor. The memory is located inside or outside the processor, and can exchange data with the processor by various known means.

  It will be apparent to one skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics of the invention. Accordingly, the foregoing detailed description should not be construed in a limiting sense in all respects but must be considered exemplary. The scope of the present invention must be determined by a rational analysis of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

  Although the scheme for performing the side link communication in the wireless communication system of the present invention has been described centering on an example applied to the 3GPP LTE / LTE-A system, it can be applied to various other wireless communication systems. is there.

Claims (10)

A method for performing side link communication in a wireless communication system,
The method performed by the first terminal is:
Receiving resource pool allocation information indicating at least one resource pool from among a plurality of preset resource pools from the base station;
Identifying a specific sidelink resource for a second terminal in the at least one resource pool;
Transmitting, to the second terminal, a signal allocating the identified specific side link resource,
The method, wherein the specific side link resource is allocated for a signal for performing a side link measurement between the first terminal and the second terminal.   The method of claim 1, wherein the at least one resource pool is allocated for a specific terminal group to which the first terminal and the second terminal belong.   The method according to claim 2, wherein the signal for performing the side link measurement includes at least one of identification information of the specific terminal group or information of a terminal order within the specific terminal group. The specific side link resource is identified according to a resource order set for the second terminal,
The method of claim 1, wherein the resource order is set based on a preset resource pattern. The preset plurality of resource pools include one or more sub-resource pools set for each terminal group,
The method of claim 1, wherein the resource pool assignment information is received via higher layer signaling.   The method according to claim 1, wherein the signal for performing the side link measurement includes a counter indicating the validity of the signal. Before the counter expires, the method further includes transmitting, to the second terminal, information indicating a new resource pool for transmitting a signal for performing the side link measurement,
7. The method of claim 6, wherein the new resource pool belongs to the preset number of resource pools.   The specific side link resource is a received signal energy value or a CBR (Channel Busy Ratio) value measured for one or more side link resources constituting the at least one resource pool. The method of claim 1, wherein the method is determined using at least one. The preset multiple resource pools include a specific resource pool for a fall-back operation associated with the side link measurement procedure,
The method of claim 1, further comprising transmitting a signal for performing the side link measurement in the specific resource pool. In the first terminal performing the side link communication in the wireless communication system,
A transmission / reception unit for transmitting / receiving a radio signal;
A processor operatively connected to the transmitting and receiving unit,
The processor comprises:
Receiving resource pool allocation information indicating at least one resource pool among a plurality of preset resource pools from the base station;
Identifying a specific sidelink resource for a second terminal in the at least one resource pool;
To the second terminal, control to transmit a signal that allocates the identified specific side link resources,
The terminal, wherein the specific side link resource is allocated for a signal for performing a side link measurement between the first terminal and the second terminal.